Exciting recent developments in giant magnetorestrictive (GMS) and magnetic shape memory (MSM) material have led to the possibility of developing small, low-cost, room-temperature, high-sensitivity, fiber-optic sensors capable of detecting human biomagnetic signals, including those from brain and heart, without direct contact with the body surface. The technical challenges associated with developing these materials into biomagnetic sensors remain to be addressed. This Phase I proposal seeks to develop a working sensor capable of detecting biomagnetic signals of the human heart. Therefore, the aim of the present proposal is: The construction, calibration and demonstration of a prototype fiber-optic biomagnetic sensor, based on giant magnetorestrictive materials, with the requisite sensitivity to monitor the magnetic signals generated by the human brain or heart. The proposed biomagnetic sensor offers high sensitivity at room temperature, and is not a SQUID-based system. SQUIDs must operate at liquid helium temperature (approximately 4 K) which require bulky cryostats, and they consume expensive, non-renewable helium. It is projected that the four sensors could be produced at costs significantly lower than SQUID-based systems, and will incur substantially lower maintenance costs due to the absence of a cryogenic support system. We anticipate that this relative ease of deployment will lead to the rapid expansion of our fiber-optic magnetometers in the clinical practice. Once the prototype is in operation, Phase II development path will include (1) the miniaturization of these sensors, (2) the incorporation of them into a portable sensor array, and (3) the development of computer software to process, analyze, and localize the resulting biomagnetic signals. The ultimate goal is to produce the Magnim Imaging System (MAGNIS), for non-invasive, high sensitivity heart and brain diagnostic/tumor imaging based on an array of biomagnetic sensors contained either in a lightweight suit or vest (for the imaging of areas of the torso) or a helmet (for the brain or cerebral tumor imaging).